Field of the Invention
The present invention relates, in general, to spray nozzles configured for use when spraying consumer goods such as air fresheners, cleaning fluids, personal care products and the like. More particularly, this invention relates to a fluidic nozzle assembly for use with low-pressure, trigger spray or “product only” (meaning propellant-less) applicators or nozzles for pressurized aerosols (especially Bag-On-Valve and Compressed Gas packaged products).
Discussion of the Prior Art
Generally, a trigger dispenser for spraying consumer goods is a relatively low-cost pump device for delivering liquids from a container. The dispenser is held in the hand of an operator and has a trigger that is operable by squeezing or pulling the fingers of the hand to pump liquid from the container and through a spray head incorporating a nozzle at the front of the dispenser.
Such manually-operated dispensers may have a variety of features that have become common and well known in the industry. For example, a prior art dispenser may incorporate a dedicated spray head having a nozzle that produces a defined spray pattern for the liquid as it is dispensed or issued from the nozzle. It is also known to provide nozzles having adjustable spray patterns so that with a single dispenser the user may select a spray pattern that is in the form of either a stream or a substantially circular or conical spray of liquid droplets.
Many substances are currently sold and marketed as consumer goods in containers with such trigger-operated spray heads, as shown in FIGS. 1A-1C. Examples of such substances include air fresheners, window cleaning solutions, carpet cleaners, spot removers, personal care products, weed and pest control products, and many other materials useful in a wide variety of spraying applications. Consumer goods using these sprayers are typically packaged with a bottle that carries a dispenser which typically includes a manually actuated pump that delivers a fluid to a spray head nozzle which a user aims at a desired surface or in a desired direction. Although the operating pressures produced by such manual pumps are generally in the range of 30-40 psi, the conical sprays are typically very sloppy, and spray an irregular pattern of small and large drops.
Sprayer heads recently have been introduced into the marketplace which have battery operated pumps in which one has to only press the trigger once to initiate a pumping action that continues until pressure is released on the trigger. These typically operate at lower pressures in the range of 5-15 psi. They also suffer from the same deficiencies as noted for manual pumps; plus, they generally have even less variety in or control of the spray patterns that can be generated due to their lower operating pressures.
Aerosol applications are also common and now use Bag-On-Valve (“BOV”) and compressed gas methods to develop higher operating pressures, in the range of, e.g., 50-140 psi rather than the previously-used costly and less environmentally friendly propellants. These packaging methods are desired because they can produce higher operating pressures compared to the other delivery methods, as mentioned above.
The nozzles for typical commercial dispensers are typically of the one-piece molded “cap” variety, having channels producing either spray or stream patterns when the appropriate channel is lined up with a feed channel coming out of a sprayer assembly. These prior art nozzles are traditionally referred to as “swirl cup” nozzles inasmuch as the spray they generate is generally “swirled” within the nozzle assembly to form a spray (as opposed to a stream) having droplets of varying sizes and velocities scattered across a wide angle. Traditional swirl nozzles consist of two or more input channels positioned tangentially to an interaction region, or at an angle relative to the walls of the interaction region (see, e.g., FIGS. 2A and 2B). The interaction region may be either square, with specified length, width and depth dimensions, or circular, with specified diameter and depth dimensions. The standard swirl nozzle geometry requires a face seal and is arranged so that the flow exits the input channels and enters the interaction region with swirling or tangential velocity, setting up a vortex. The vortex then circulates downstream and leaves the interaction region through an exit which is typically concentric to the central axis of the nozzle assembly.
The problems with the prior art nozzle assemblies of FIGS. 1A-2B include: (a) a relative lack of control of the spray patterns generated, (b) frequent generation in such sprays of an appreciable number of both large and small diameter droplets which are randomly directed in a generally distal direction, and (c) a tendency of the resulting spray patterns to create sprayed areas pelted with large high velocity liquid droplets which result in the sprayed liquid splattering or collecting in pools that produce undesirable, break-out portions that stream down a sprayed surface. Sprays with large droplets are particularly undesirable if the user seeks to spray only a fine mist of liquid product. Droplets comprising a “mist spray” preferably have a diameter of eighty micrometers (80 μm) or less, but should be larger than 10 μm to avoid inhalation hazards; however, prior art swirl cups cannot reliably create misting sprays with droplets of the desired size range of, e.g., 60-80 μM.
As described in the above-mentioned commonly owned U.S. Pat. No. 7,354,008 to Hester et al, a spray head nozzle for the above-described dispensers may incorporate a fluidic device that can, without any moving parts, yield any of a wide variety of spray patterns having a desired droplet size and distribution. Such devices include fluidic circuits having liquid flow channels that produce desirable flow phenomena, and such circuits are described in numerous patents. The Hester patent describes fluid circuits for low pressure trigger spray devices.
Swirl nozzles are used in numerous applications. The primary function is generating an atomized spray with a preferred droplet size distribution. For many applications, it is preferred that the sprayed droplet Volumetric Median Diameter (VMD or DV50) and domain of the distribution be as small as possible. It is also desired to minimize the operating pressure required to generate a preferred level of atomization. There is a need, therefore, for a cost effective substitute for the traditional swirl cup, which will reliably generate droplets of a selected small size so as to avoid the splattering and other disadvantages of large droplet creation by traditional swirl cups in relatively high pressure applications such as hand operated pumps that can generate pressures in the range of 30-40 psi, or for “BOV” and compressed gas devices that develop higher operating pressures, in the range of, e.g., 50-140 psi.